1 grind sth (down/up);grind sth (to/into sth) to press and break sth into very small pieces or into a powder between two hard surfaces or in a special machine 磨碎: Wheat is ground into flour. 小麦磨成面粉。ground pepper/coffee 胡椒╱咖啡粉

2 to make sth sharp or smooth by rubbing it on a rough hard surface 磨快: to grind a knife on a stone 在石头上磨刀

3 grind sth in/into sth to press or rub sth into a surface 用力挤或擦: He ground his cigarette into the ashtray. 他把香烟掐灭在烟灰缸里。

4 to rub sth together or make sth rub together, often producing an unpleasant noise （使）磨擦（常发生刺耳声响）: Some people grind their teethwhile they're asleep. 有些人睡着时会磨牙。